1. Field of the Invention
The present invention relates to a broadcast receiving device provided with a channel scanning function and a method for renewing channel information in the broadcast receiving device.
2. Description of the Related Art
A broadcast receiving device, which is provided with an automatic channel-scanning function for automatically detecting receivable channels when it is installed in a house after it has been purchased or after moving, has been known (see JP-WO98/15118: Patent Document 1; and JP2001-16524A: Patent Document 2). In conducting such an automatic channel scanning function, a tuner is made to tune in on channels one by one for detection of broadcast signals, and detected channels in which a broadcast signal exists and frequency data of those channels are coordinately stored in a channel memory as a receivable channel.
Also, another television broadcast receiving device is disclosed, for example, in JP 2006-41751A (Patent Document 3), in which new channel information to be registered for a channel newly detected as a tunable channel is added to a channel information table with the registered channel information on channels already registered as tunable channels being retained as it is so that the already-registered channels are prevented from being treated as un-tunable channels when a new channel scanning process is conducted.
In general, intensity of a television-broadcasting signal, i.e. a transmission condition of a transmission path, varies depending on a receiving time slot of day, a location where a television-broadcast receiving device is installed, and a weather condition, as the transmission condition is subject to the influence of those factors. Therefore, as the tunable channels and un-tunable channels may sometimes alter in response to the condition of those factors. When the channel scanning processing is conducted, as disclosed in the Patent Documents 1, 2, and 3, without considering changes of the transmission conditions in the transmission path, un-tunable channels may occur in spite of the fact that they are registered in the channel data as tunable channels. This generates a problem in that the usability or user-friendliness of the television broadcast receiving device will be deteriorated.